1. Field of the Invention
The present invention relates to a method of determining hydrogen peroxide for quality-controlling a commercially available aqueous solution containing hydrogen peroxide or another substance containing hydrogen peroxide, or in a hydrogen peroxide formation or decomposition system in chemical reaction such as enzyme reaction, and an apparatus which is employed therefor.
2. Description of the Background Art
In relation to determination of hydrogen peroxide in an aqueous solution, the following methods are known in the art:
(1) A method employing a hydrogen peroxide electrode. PA1 (2) Leuco or oxidation condensation type spectrophotometry (refer to Japanese Patent Laying-Open Gazette No. 59-182361 (1984)), which is typically adapted to react hydrogen peroxide with 4-aminoantipyrin and phenol for coloring, and to measure absorption of the coloring reaction solution at 505 nm. PA1 (3) A fluorescent method, which is adapted to react hydrogen peroxide with homovanillic acid to generate fluorescence, and to measure the fluorescence. PA1 (4) Chemiluminescence, which is adapted to excite a substrate of luminol or lucigenin through oxidizing power of hydrogen peroxide under presence of a catalyst such as POD (peroxidase) and to detect light generated when the substrate returns from the excited state to the ground state. PA1 .theta.&gt;.theta.c
The aforementioned methods (1) to (4) of determining hydrogen peroxide in aqueous solution samples have the following problems:
The method (1) is adapted to measure current change which is caused when hydrogen peroxide is electrically oxidized, and hence an influence is exerted by a reducing substance coexisting in the sample solution.
In the leuco type spectrophotometry (2), an error is readily caused by coloring of a reagent blank resulting from natural oxidation of a chromogen. In the oxidation condensation type spectrophotometry (2), on the other hand, a negative error is readily caused by a reducing substance. Further, hydrogen oxide of 2 moles is required for forming a pigment of 1 mole, and hence this method is unsuitable for determination of a component of a small quantity.
In the fluorescent method (3), sensitivity remarkably depends on the performance of an apparatus. Thus, this method is extremely influenced by a temperature and a coexistent substance.
In the chemiluminescence (4), a sufficient quantity of light emission is obtained only under alkaline conditions. The reaction rate is slow and reproducibility is insufficient. Further, light emission intensity is reduced upon coexistence of protein.